Pulsation relief device



Sept. 5, 1944. H. J. wlsER PULSATION RELIEF DEVICE Filed June 23, 1941 'Ilfflfi/lillrllllv. .llt/ll IN VEN TOR.

Patented Sept. 5, 1944 UNITED y STATESA PATENT DFFICE f azs'vzzfv ff I rULsA'rIoN RELIEF nevica Hubert J. Wiser, Bloomington, Ill., assigner to Williams Oil-O-Matic Heating Corporation, Bloomington, Ill., a corporation o! Iliinois Application June 23, 1941, serial No. 399,245

' solemn. (ci. 15s- 76) This invention relates to liquid fuel burners and is particularly adapted for use in connecf tion with domestic heating plants, although it may successfully be used with other typesl of burnerA installations. In installations of this type it is diiiicult to control the air supply to the combustion chamber in a manner to prevent pulsation therein and at the same time control the combustion so that the escape of fumes from the combustion chamber is prevented.

In liquid burner installations considerable difiiculty is experienced with pulsation in the combustlon chamber, the formation of soot in furnaces or boilers, dirty electrodes in the ignition system, a noisy fire, and a high percentage of excess air. It is therefore an object of the present invention to provide an air control and pulsation relief device whereby the above-mentioned dimculties are overcome and eilicient combustion is assured with a material reduction in the excess air required. In other words, the pulsation pressure ordinarily due to back draft is relieved in such a manner that the fumes do`not escape into the furnace room from the burner installation and at the same time the excess air is reduced, the carbon dioxide is increased, and the stack temperature lowered. These advantages are all obtained by a proper back draft circulating system' which is automatic in its action and does not require the use of any additional operating devices and may easily and economically be applied to the usual burner so as to meet any ordinary requirements.

Further objects will be apparent from the following disclosure.

'In the drawing:

Fig.-1 is a side elevation partially in section oi' a standard oil burner and stack and illustrates one embodiment of the invention associated therewith.

Fig. 2 is a top view of the pulsation relief housing associated'with-the usual draftfan.

Fig. 3 is a sectional view taken on a line substantiallycorresponding to line 3*--3` of Fig. 1.

Fig. 4 is an enlargeddetail view partially inl section of the burner end ofthe draft pipe with stalled in connection with the usual combustion chamber. The burner comprises a support I on which is mountedl a fan casing 2. The usual blade fan 3 is enclosed in the fan casing and operated in the usual manner by a motor 3a. 'I'he fan has the usual central air inlet and a peripheral outlet for directing air through a draft pipe 4 into the usual combustion chamber 5 of a furnace or the like. The furnace is provided with the usual inner wall Ii of refractory material and an outer casing l to provide a space 8 therebetween to provide a means for passing the flue gases to the boiler stack 8a. vThe draft pipe 4 is supported on the casing 2 and may be of the usual construction and provided at its forward end with the usual air cylinder 9 secured therein and having spiral iins I0 forming bailies arranged to provide a whirling motion of the air around the tip of an oil nozzle II.

The oil nozzle II is supported on the outer end of an air supply pipe I2a, which latter is axially positioned around an oil tube I2. The air supply pipe I2a is axially positioned in the draft pipe 4 by means of a, support I3.- The fuel supply pipe I2 and the air supply pipe I2a extend-through the fan casing 2 and are connected in the usual manner with an oil'supply from which oil is delivered to the nozzle by means of an oil suction pump I4a,- an oil valvejassembly I3a, and a diifuser I4, whichare automatically controlled in accordance with fuel requirements in the usual manner. A cone-shaped air spreader I5 is mounted on the pipe I2a adjacent the nozzle and is preferably formed of porcelain for` the like. This spreads the air from the fanA against the inside wall of the draft pipe adjacent the nozzle II. The oil is atomized in the nozzle' II by the primary air entering through the air v tube I2a and it is thoroughly mixed with 'the' whirlingsecondary air delivered Zthrough the draft tube'4. thereby producing'area'dil'yA com`- l bustible mixture. For purposes of ignition, suitparts broken away to show the interior conbetween the` fuel nozzle andthe combustion chamber.

Referring' to the drawing in detail, the emable electrodes I6 are positioned adjacent thel nozzle tip and connected to the usual ignition curely thereinsothat no gases from the commounted' o n a bracket I9 secured to thefan casbodiment illustrated in Figs. 1 to 4 comprises a ing. 2. '1 'I'he casing I8 is of sufficient size to provide an annular yair passage' 20 around the draft the periphery where there is no material pres.y

sure or draft. The pulsation chamber, therefore, communicates, through thefan casing and draft pipe 4, with the combustion chamber, al-

though, on account of the opening 22 being at a` neutral point of the fan, air will not circulate through vthe passage 22 except when vat least some pulsation p ressure exists in the pulsation relief chamber 2|. It will be apparent that any back pressure from the combustion chamber will be relieved through the annular passage 20 into the pulsation relief chamber and through the fanand draft pipe to the burner.

The outer casing I8 is, of course, securely cemented into the furnace walls as shown. The

annular'spaee between the draft pipe 4 and the draft pipe casing I8 may be about fag of an inch in ordinary practice, and a series of holes 23 is provided through the draft pipe 4 between the spreader l5 and the tip of the nozzle Il. These holes 23 may be spaced as required and are in practice usually about 1A, inch in diameter. The series of holes is preferably located just back of the air cylinder 9. When the device is in operation, the porcelain air spreader I5 spreads the air from the fan against the inside wall of the draft pipe 4. This forces a certain amount of air through the portholes 23 and, due to the back draft in the combustion chamber, the air from thepgrtholes flows rearwardly through the annular passage into the pulsation relief chamber 2l, then through the fan and draft pipe 4 to the combustion chamber. When the burner starts, pressure is setup in the combustion chamber and this pressure is immediately relieved in the manner described.

The pulsation reliefv device successfully operates under practically' all normal working conditions, that is, when there is pressure in the combustion chamber, when there is a balanced condition (with no draft at all), or under substantially any draft conditions in the combustion chamber. It operates successfully in connection with either low or high pressure burners. It prevents resonant peaks of pressure and reduces the excess air required to a more economical point and a greater combustion efficiency is therefore obtained. It also eliminates the high static pressure usually used to overcome pulsation with larger fans. It tends to increase the CO2 and to lower the stack temperature. The air flow between the draft pipe and the draft pipe sleeve has a tendency to cool the air pipe, thereby prolonging its life. The air flow also acts to prevent burning of the air cylinder vanes and the nozzle andfurnishes air for combustion as well. `Fi^g`. 5 illustrates an embodiment in which the pulsation relief chamber 2l may be eliminated and an additional sleeve 24 is mounted on the forward end of a draft pipe 4 to provide an annular chamber 25 around the series of holes 23 and communicating with the combustion chamber 5. In this construction the holes 23 provide means for equalizing the pressures in the combustion chamber and in the draft pipe 4 behind the spiral fins I0. Thus in normal operation, air passes through the holes 23 into the annular chamber 25 and into the combustion chamber 5. This circulation provides a cooling eifectwhich prevents burning of the air cylinder 9 andthe oil nozzle Il, On the other hand, when there is an excess pressure in the combustion chamber 5,

the pressure is relieved back into the draft pipe 4 through the holes 23.

It is intended, of course, that the invention should not be limited to the speciflc embodiment or embodiments disclosed herein, since modifications may be made, and it is contemplated, therefore, by the appended claims to cover any such modifications as fall within the true spirit and scope of this invention. l

Having thus described this invention, what is claimed and desired to be secured by Letters Patent is: v

- 1. In a liquid fuel burner having a draft pipe and a fuel discharge nozzle in said pipe adjacent the outlet end thereof and directed toward said outlet end, means for providing a forced draft through said pipe and into a combustion chamber, and a pulsation relief conduit from said combustion chamber and communicating with said draft pipe adjacent said nozzle and also communicating with said forced draft means through an inlet constructed and positioned relative to said draft means to normally maintain a substantially neutral pressure inv said conduit.

2. In a liquid fuel burner having a draft pipe and a burner nozzle therein, said draft pipe at its outlet communicating with a combustion chamber, means for providing a forced draft through said pipe and into the combustion chamber, and an annular pulsation relief conduit extending from said combustion chamber around the nozzle end of said draft pipe and spaced therefrom and communicating with said draft pipe closely adjacent said nozzle through a series of small passages through the wall of said draft pipe.

3. In a liquid fuel burner having a draft pipe and a burner nozzle therein, said draft pipe at its outlet communicating with a combustion chamber. means for-providing a forced draft through said pipe and into the combustion chamber, an air spreader in said draft pipe adjacent said nozzle, and an annular pulsation relief conduit extending from said combustion chamber around the nozzle end of said draft pipe and spaced therefrom and communicating with said draft pipe through a series of small passages positioned between said air spreader and said nozzle.

4. A burner construction of the character described comprising a combustion chamber, a draft pipe opening into said chamber, a burner nozzle positioned within said draft pipe, spiral ns within said draft pipe interposed between the end thereof opening into the combustion chamber and the burner nozzle, an annularly spaced casing around said draft pipe providing a pressure relief passageway communicating with said combustion chamber, and means for providing a forced draft through said draft pipe, said draft pipe having apertures therein providing direct communication for the ow of gases between said draft pipe and said pressure relief passageway.

5. The burner construction recited in claim 4 wherein the forced draft providing means is a blower of the centrifugal type and wherein the pressure relief passageway also communicates with said blower through a peripheral blower casing inlet constructed and positioned relative to the blower rotor-to normally maintain a substantially neutral pressure at said inlet.

6. In a liquid fuel burner, a draftpipe having the outlet end thereof communicating with a combustion chamber, a burner nozzle in said draft pipe adjacent the outlet end thereof, a fan blower having a casing with its outlet connected to one end of said draft pipe to provide a forced draft therethrough and into the combustion chamber, and a pressure relief conduit connected to said blower casing through an inlet positioned and constructed relative to said blower to normally maintain a substantially neutral pressure in said pressure relief conduit, said conduit terminating closely adjacent the outlet end of said draft pipe for communication with said combustion chamber.

' '1. In a liquid fuel burner having a draft pipe communicating with a combustion chamber and a fuel nozzle in said pipe adjacent said chamber, an air spreader in said pipe back of said nomle and adjacent thereto for directing the draft current toward the wall of said pipe. said pipe having an annular series of relatively small perforations through the wall thereof between said spreader and the outlet end of said nozzle, a centrifugal type blower having its casing outlet communicating with said draft pipe, and a casing forming an annular passage around said pipe and communicating with said combustion chamber and also communicating with said blower through a casing inlet constructed and positioned relative to said blower to normally maintain a substantially neutral pressure in said annular e. t s

8. Ina liquid fuel burner, a draft pipe having the outlet endi; thereof communicating with a combustion chamber, a burner nozzle in said 10 draft pipe adjacent the outlet end thereof, said draft pipe havixikfa restricted passage therein adjacent said burner nozzle and 'back'of the tip thereof, a fan ower having a casing with its outlet connec to said draft pipe to provide a u, forced draft therethrough and into the combustion chamber, d a pressure relief conduit connected to said b wer casing through an inlet positioned and consti. cted relative to said blower to normally maintain a substantially neutral pres- 20 sure in said prellre relief conduit. said draft pipe `being aperturedl to afford direct communication between said draft pipe and said relief conduit. the apertured portion of said draft pipe being closely daiacentzthe outlet end thereof for com- 25 munication of said relief conduit with said combustion chamber.

HUBERT J. WISER. 

